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Types of Chemical Reactions

An animal cell. There are around 10 trillion cells in the human body. Image courtesy of http://monstara.deviantart.co

Chemical reactions are the “machinery” that drive our universe. For example just in one adult human body there are billions maybe even trillions of chemical reactions that occur every second.[1] We can categorize these chemical reactions based on what happens to the reactants and the products that result. Most chemical reactions will fall into one of five categories:

Synthesis Reactions

Decomposition Reactions

Single Displacement Reactions

Double Displacement Reactions

Combustion Reactions

Let’s learn how we can distinguish between the five types of chemical reactions.

Synthesis Reaction

Synthesis reactions are distinguishable because they produce a single product from only two reactants. Also, the reactants are usually in their elemental form. Here is the general form of a synthesis reaction:

Synthesis Reaction

And here is an example of a synthesis reaction:

Synthesis of water

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Decomposition Reaction

Decomposition reactions are the opposite of a synthesis reaction and are distinguishable because they have one reactant that becomes two products. Here is the general form of a decomposition reaction:

Decomposition Reaction

And here is an example of a decomposition reaction:

Decomposition of Hydrogen Peroxide

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Single Displacement Reaction

A single displacement reaction is generally distinguishable because they have a single metal and an ionic compound on the reactant side of the equation as well as on the product side of the equation. Single displacement reactions generally occur when a more reactive metal replaces another metal out of an ionic compound. Here is the general form of a single displacement reaction:

Single Displacement Reaction

And here is an example of a single displacement reaction:

Single Displacement with Iron and Lead (II) Nitrate

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Double Displacement Reaction

A double displacement reaction is distinguishable because there are two ionic compounds on the reactant side of the equation and two ionic compounds on the product side of the equation. In a double displacement reaction the anions and cations of the two ionic compound reactants will switch places, forming new ionic compounds. Double displacement reactions generally take place in an aqueous environment and produce a precipitate, gas or a liquid. Here is the general form of a double displacement reaction:

Double Displacement Reaction

And here is an example of a double displacement reaction:

Double Displacement Reaction of Calcium Bromide and Silver Nitrate

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Combustion Reaction

A combustion reaction is distinguishable because the reactants will be a hydrocarbon and oxygen gas (O2). The products of a complete combustion reaction will always be water, carbon dioxide and heat. In an incomplete combustion reaction carbon monoxide (CO) will be produced along with the water and carbon dioxide. Here is an example of a combustion reaction:

Combustion of Methane

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You may have noticed the letters after the chemical formulas in the chemical equations. These symbols describe the state of those chemical compounds. Here’ s are the symbols used in chemical equations: